STUDIES ON LOW RARE-EARTH ND-FE-B COMPOSITIONS

Investigations have been carried out to evaluate the optimum Nd-Fe-B composition to have H-ci of at least 4 kOe. The otpimum composition for the best magnetic properties is as follows: TRE 18 wt. %, B 1 wt. % and balance Fe. The magnetic I,roperties are B-r, 10.1 kG, H-ci 4.3 kOe and BHmax 12.5 MGOe. All the additives (Ga, Nb, Mo, V, Cr) with or without cobalt addition did not improve the magnet properties. The bonded magnets made using this material had B-r value slightly higher than the standard MQP-B powder. The low coercivity of these materials limit their operating temperature to 80 degrees C. This material having Nd2Fe14B/proportional to-Fe structure shows improved saturation behavior compared to those having Nd2Fe14B/Fe3B and Nd2Fe14B structures. It would then be a good candidate for applications where magnetization is difficult.